This is a great skill in theory, but not so good a skill in practice, especially not for 'the bard's ulimate skill'.
I've been trying a few things with this skill, such as persuading npcs to cast nice spells on me. Here are examples of the skill NOT working.
Quote:
A rosy-cheeked female gnome utters the words, 'grzzs'.
A wildcat goes to sleep.
Here we see that the npc in question a rosy-cheeked gnome CAN cast the spell 'sleep'
Quote:
> persuade rosy cast sleep
Ok.
[HP:100%] [ME: 55%] [PE:100%]
>
A wildcat tries to trip a rosy-cheeked female gnome but ends up tripping itself!
[HP:100%] [ME: 55%] [PE:100%]
>
A rosy-cheeked female gnome starts to concentrate.
[HP:100%] [ME: 55%] [PE:100%]
>
A rosy-cheeked female gnome utters the words, 'aque bragh'.
A rosy-cheeked female gnome's blast of acid sprays a wildcat, sizzling and burning its skin!
[HP:100%] [ME: 55%] [PE:100%]
> persuade rosy hug cat
A rosy-cheeked female gnome hugs a wildcat.
Ok.
This is later on, another combat round. Ensuring the gnome has the concentration to cast the spell. As you can see, I have a successful persuade. Simply typing out cast sleep when in combat SHOULD make you cast sleep on the first opponent. Having played a caster and used sleep many times in that way, I know it works. In this example we see the persaude claims to succeed and then the gnome goes ahead and doesn't do what it in theory was just persuaded to do.
We then at the end see another succesful persuade, this time simply asking the damned thing to do a social which is has no problem what so ever doing. Conclusion? I think persuade is bugged. So far I have not been able to persuade any npc to cast any spell, reguardless of if it has the int, mana and concentration to do it, they just won't cast. This isn't listed as something you can't use persuade to do and I'm pretty sure you can persuade pcs to cast, so why not npcs?